Area Forecast Discussion
Issued by NWS Mobile, AL
Issued by NWS Mobile, AL
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811 FXUS64 KMOB 231120 AFDMOB Area Forecast Discussion National Weather Service Mobile AL 620 AM CDT Mon Sep 23 2024 ...New AVIATION... .AVIATION... (12Z TAFS) Issued at 620 AM CDT Mon Sep 23 2024 A few patches of fog early this morning will dissipate shortly after sunrise. Patchy fog will be possible again late tonight, otherwise VFR conditions are expected. A southerly to southwesterly flow at 5 to 10 knots develops today, then winds become light and variable this evening. /29 && .PREV DISCUSSION... /issued 454 AM CDT Mon Sep 23 2024/ ..New NEAR TERM, SHORT TERM, LONG TERM, MARINE... NEAR TERM... (Now through Tuesday night) Issued at 454 AM CDT Mon Sep 23 2024 An upper ridge over much of the Gulf and adjacent northern Gulf coast states is deflected out of the forecast area through Tuesday in response to a longwave trof which evolves over the central states and begins to advance into the eastern states. A surface ridge will be oriented near/along the northern Gulf coast today and remains close to this position into Tuesday, and this allows for a southerly to southeasterly flow to become established over the forecast area today and continue into Tuesday. Despite the movement of the upper ridge, waning subsidence effects look sufficient to suppress convective development, although can`t rule out a shower or storm developing each afternoon. Highs today mostly range from 90 to 95, then highs on Tuesday will be mostly in the lower 90s. Lows tonight and Tuesday night range from around 70 inland to 70-75 near the coast. A low risk of rip currents is expected through Tuesday night. /29 SHORT TERM... (Wednesday through Friday) Issued at 454 AM CDT Mon Sep 23 2024 Overview... We continue to monitor an area of low pressure that is beginning to show signs of development over the Western Caribbean. This feature (which has recently been designated Invest 97L) is currently a part of a larger scale Central American Gyre (CAG), and will continue to organize over the next few days. This system now has a 70 percent chance of developing into a tropical cyclone over the next 48 hours and a 90 percent chance over the next 7 days. With a trackable feature now in place, model guidance this morning is slowly starting to become a little more aligned with regards to the system`s overall trajectory. In addition, with the storm acquiring an `invest` designation, high resolution hurricane-specific models (HWRF, HMON, etc.) are now being utilized for this system to help answer intensity-related questions. As is the case with the global models, it should be stressed that any one particular run from these models should not be taken at face value. That being said, it should be noted that the full suite of these models are offering hints at a rather quick intensification period as the storm begins its trek into the Gulf. Due to continued uncertainties with the upper-level steering patterns at play and how fast the system can intensify, there is still a variety of solutions that are being presented (giving way to a continued low confidence track and intensity forecast) and additional changes will still be possible over the next day or two. I will once again break down the remainder of the discussion into a "what we know" section and a "what we don`t know at this time" section. What we know... As stated above, Invest 97L has formed just off the coast of Nicaragua and Honduras. Although activity is still rather disorganized, pockets of deep convection are continuing to bubble up around the developing center of circulation. Environmental conditions are certainly conducive for further development thanks to the very warm water temperatures in that region and being located underneath an upper-level anticyclone (which is giving way to low wind shear). 97L will initially be steered north-northwestward around the larger-scale CAG feature, crossing through the Yucatan Channel and arriving in the southern Gulf by Wednesday. At this point, the system will start to break off from the CAG and will start feeling the steering effects of the upper-level features to its north. The known steering features include: an upper ridge located over the southeast US and a longwave trough digging into the central US. With regards to the trough, almost all models over the past 24 hours have aligned with the solution that suggested that the upper trough will dig far enough south to break off from the northern jet stream, resulting in an anomalously large upper low that parks itself near the Mississippi River Valley. This will help to break down the ridge and allow for 97L to lift northward over the eastern Gulf. Although the exact path is still uncertain at this time, guidance is coming into fairly good agreement that 97L`s eventual path will likely result in a landfall somewhere along the Florida Panhandle/Big Bend area, and with the favorable conditions in place, it is a good chance that it will make landfall as a hurricane. A few additional things to keep note of... 1) Models continue to suggest that this system will be quite large, so even though the eventual track of this system is rather murky, hazardous marine conditions, dangerous surf, and life threatening rip currents will likely be felt across a majority of the Gulf Coast region, regardless of track. 2) Once 97L gets picked up by the upper low, it will move to the north very quickly. While this is good news from an impacts standpoint (as the storm is not going to linger around for multiple days), this will leave very little time for preparations, especially if one is waiting for the system to develop and acquire a name/cone/etc. Although impacts from the system would not begin until Thursday, numerous showers and storms are expected out ahead of the system on Wednesday. Therefore, if you need to make any preparations, it is recommended to take advantage of the dry days we have (today and tomorrow) to do so. What we don`t know at this time... Thankfully today we have more answers than we did this time yesterday, although there are still a lot of uncertainties when looking at the finer details. The first question is, where exactly will the core of the storm go? As stated earlier, models are beginning to focus in on a landfall somewhere along the Florida Panhandle/Big Bend area. While most guidance cluster it to the east of our area at this time, that is not to say we are out of the woods. Expect models to continue shifting back and forth over the next day or so as they continue to resolve the placement of the upper cutoff low. A further west upper low will result in a landfall closer to our area (more impacts for our CWA), while a further east upper low pushes the landfall location closer to the Big Bend area (less impacts for our CWA). At this time, we just do not know exactly what will transpire and therefore, we cannot, with confidence, hone in on specific impacts at this time. But as stated before, even if the center does not directly strike our CWA, impacts will likely be felt far removed from the center of the system due to its expected size. Hopefully over the next 24 to 36 hours, we will be able to focus more on our local impacts. The other question is how strong will the storm get? The answer to that is still yet to be determined. For most of its journey across the western Caribbean and eastern Gulf, signs are pointing to a continued pattern that favors strengthening (high water temps, low shear, and a rather moist environment). There could be an increase in wind shear over the northern Gulf and a possibility that some dry air may attempt to wrap into the system as it becomes intertwined with the upper low, but overall, all signs point to strengthening, potentially into a hurricane. With the favorable conditions in place, cannot rule out a bout of rapid intensification as it moves into the Gulf. We will continue to monitor trends closely and we urge residents and visitors across the entire central/eastern Gulf Coast to continue to monitor the forecast, check their hurricane kits, and evaluate and refresh any needed supplies. /96 LONG TERM... (Friday night through Monday) Issued at 454 AM CDT Mon Sep 23 2024 There is some uncertainty with the overall pattern early in the period which depends on how an anticipated tropical system affects the region. Please see the National Hurricane Center for more information. Otherwise, an upper low is expected to be centered over Arkansas/Louisiana/Mississippi then slowly weakens and lifts off into the interior eastern states through Monday. Have opted to continue with a dry forecast for Friday night with deep layer dry air anticipated to have moved into the area, then slight chance pops follow for the eastern half of the area on Saturday as deep layer moisture improves. Rain chances could end up being limited on Sunday and Monday depending on how the pattern plays out, but for now have gone with slight chance to chance pops and will reassess on later shifts. /29 MARINE... Issued at 454 AM CDT Mon Sep 23 2024 No impacts are expected through Wednesday afternoon other than higher winds and seas near storms. For Wednesday night into Thursday, a potential tropical system could bring significantly higher seas and strengthening winds to the marine area. Please see the National Hurricane Center for more information. Winds and seas are expected to subside Thursday night into Friday night, although there is uncertainty regarding how quickly this occurs. /29 && .PRELIMINARY POINT TEMPS/POPS... Mobile 93 71 91 71 86 70 79 68 / 0 0 10 20 70 70 70 40 Pensacola 91 74 89 75 85 72 79 71 / 0 0 10 30 70 80 80 40 Destin 90 75 88 75 85 73 80 74 / 0 0 10 30 60 80 80 50 Evergreen 95 68 93 69 87 70 79 68 / 0 0 10 20 70 80 80 50 Waynesboro 93 69 92 69 87 67 80 67 / 0 0 10 20 60 50 60 40 Camden 93 70 92 69 85 68 77 67 / 0 0 0 30 70 70 70 50 Crestview 94 69 93 70 86 71 79 67 / 0 0 10 30 70 80 90 50 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: www.weather.gov/mob